Dimpling and depth controlling attachment for fastening member driving tools



Dec. 29, 1959 A. J. sMrrH DIMPLING AND DEPT H CONTROLLING ATTACHMENT FORFASTENING MEMBER DRIVING TOOLS 3 Sheets-Sheet Ill Filed Aug. 11, 195eDec. 29, 1959 A. J. sMrri-l 2,918,575

DIMPLING AND DEPTH CONTROLLING ATTACHMENT FCR FSTENING MEMBER DRIVINGTOOLS 3 Sheets-Sheet 2 Filed Aug. 11. 1958 ARTHUR J. SMITH /N VEN TORHUEBNER 8 WORREL TTORNEYS Dec. 29, 1959 A J SMITH f 2,918,675

ROLLING ATTACHMENT DIMPLING AND DEP''H 'CONT FOR FASTENING MEMBERDRIVING 'rooLs 5 Sheets-Sheet 3 Filed Aug. ll, 1958 /195 f 74k`\,/ /30.m130/045%) ARTHUR J. SMITH IN1/ENVOI? HUEBNER 8 WORREL ATTORNEYS nitedStates Patent DnvrrLlNG AND DEPTH co1-rmoLr.n-r ;:'A'nrrrcrr-` Mags FonFASTENING MEMBER' DRIVING Arthur J. Smith, Visalia, Calif., assignor toCalwire, Visalia, Calif., a corporation of California ApplicationAugustl 11, `1958, Serial No. 754,188n

5 Claims. (Cl. 1-44.4)

` The'present invention relates to a depth controlling attclirnent forfastening member driving toolsand more particularly to such anattachment for powered tools utilized in the mounting of wallboard,shingles, plastic sheathing, paper, and like workpieces on suitable sup`ports therefor, which attachment enables precise driving control and theattainment of a driving eifectsimilar` to 'the final blow of a manuallyemployed hammer in driving home a nail, staple or like fastener forciblyto secure the workpiece in placeand optionally` to dimple the same.

` Conventional power driven staple and nail driving tools `are known torecoil at the instant of actuation and thus by the time the drivingmembers or hammers' thereof reach the ends of their driving strokes,their tools are to some extent in a recoil position. It is thus thepractice'to constructsuch tools so that their driving memher`s` protrudeapproximately one-eighth of an` inch a't the ends of their drivingstrokesso as to compensate for the recoil. While such protrusion hasbeen required in the prior art, it has led to certain diiculties. Forexample, when nails or staplesare driven into gypsum lath, wallboard, orthe like, the depth of embedment varies somewhat. Such materialsfrequently include relatively thick core layers of gypsum or othermaterial having opposite surfaces sheathed with papen If the staples ornails are not' driven sufliciently deeply, their heads or crownsprotrude from the surface and the boards are not held tightly againsttheir supports. Onthe other hand, ifthey arev driven too deeply,thesheathing `is ruptured'. Since the core layers of such lathortwallbo'ardare fre'- quently of gypsum or other material of'little"strength, therrupturing off the paper frequently precludes proper and"`dependable mounting. y

The inherent inaccuracy in the driving depthrof such known driving toolshas severely limited"` their utility. For example, they areconventionally used to fasten gypsum lath and the like to verticalstudding" or hori- 'zontal ceiling joists since the subsequent coveringof the lath with plaster conceals insufficiently embeddedstaples andnails as well as any rupturing of the surface sheathing. However, suchdriving inaccuraciesare intolerable in drywall construction where thedry Wallboards are not plastered but only painted, papered, or`otherwise thinly covered, the painting, papering or otherV thin coatingfailing to conceal insufficiently driven staples or nails and rupturedsheathing.

Further, it is well-known that such conventional staple and' naildriving tools lack the attribute of" dependably forcing la workpieceagainst 'its supporting studs, joists of the like inthe manner of theiinalblow `with themrnan u`ally' employed hammer. Such finalblow'noi'mally con; tacts the workpiece and drives it tightly/'againstlits support as Well asconcurrently seeurin'g1`the` stapleorinailproperly inplace.

In= dry wall construction;- it is`l normallyV necessary to dmplethesurfaces. of the wallboard beingmounted so that `the heads or crowns ofthe nails or stapleslacan ICC properly `lne-concealed with a thinsurface deposit cfa Accordingly, it is an object of the presentinvention to-- provide an attachment for a tool adapted to insert adriven member into a workpiece in such a manner as preciselyr to limitthe extent of penetration of the driven member into the workpiece.

Another object is to provide in a` power driven fastenJ ing `tool forthe functional equivalent `to the iinal blow of` amanually employedhammer in driving a nail, staple` or'the like into place.`

Another object is to prevent or minimize tearing ofy the relatively'thin sheathing of wallboard or the like by a staple, or other fasteningmember, driven therein.

y Another object is` to provide a power driven tool for, fasteningawallboard or the like tightly to a` support in anexpeditious anddependable manner.

Another'object is to provide a power driven fastening tooladapted toforce wallboard, shingles, plastic sheathing, paper and the like againsta support therefor while fastening the same to the support.

Another object is to provide a pneumatically oper.- atedto`olfor'driving staples and other fasteners into such a workpieceincluding arelatively thin sheathing, and to dimple the workpiece so that thestaples are inserteda' predetermined distance into the workpiece, allwithout fracturing the sheathing with the crowns, or heads, of thestaplesor other fasteners.

Another object is to provide an attachment for a powered fastenerdriving device adapted to dimple work# pieces, into which the fastenersare driven by the device, concurrently with the driving thereof.

Another object is to` provide a device for fastening relatively thinmaterial, such as thin plastics, paper andy the like, to a supportwithout tearing the material.

`Another object is to provide improved means for compensating for recoilin fastener driving tools.

A further object is' to provide such an `attachment which automaticallyregulates the depth of fastener driving in relation to adriving headprovided for the purpose so that the staple is embedded to a depthhaving predeterminedrelation to the surface of the material receivingthe fastener whether it is dimpled or not.

These, together with other objects, will become more fully apparent uponreference to the following description and accompanying drawings.

In the drawings:

Fig. 1 is a longitudinal section' taken through a tool including theattachment of the present invention.

Fig.2 is"a fragmentary top plan view of a portion of thetool of Fig. 1showing the subject attachment in particular.

Fig. 3 is a View of a portion of the tool similar to that shown in Fig.l but with the tool in a driving position immediately followinginsertion of a staple through a wallboard into a stud therebehind.

Fig. 4is a transverse section taken on a plane at a position representedby line 4-4 of Fig. 3.

Fig. 5 is a view similar to Fig. l but showing a fragmentary portion ofthe driving tool having a second form rof attachment of'the presentinvention mounted thereon.

Patented Dec. 29, 1959.-

body having an elongated substantially cylindrical housing 11 providingan internal cylinder 12 having open opposite forward and rearward ends13 and 14, respectively. The housing has an inwardly disposed annulargroove 15 intermediate the opposite ends thereof. Also, the housingincludes an elongated manifold 17 circumscribing the cylinder adjacentto the rearward end thereof. The manifold communicates with the cylinderthrough a port 18. A cap 20 is attached to the housing over the rearwardopen end thereof in closing relation thereto. As will be noted, theforward end of the cylinder is of a smaller diameter than the rearwardend thereof.

An elongated downwardly extended handle is integrally connected to thehousing 11 and encloses a reservoir 26 adapted for connection to asource of air under pressure, not shown, by means of an air hose 27.Also, the handle encloses a valve 28 including a valve chamber 29connected to the chamber 17 by means of an air duct 30. The housingprovides an elongated bore 31 interconnecting the groove 15 and thereservoir 26. An annular valve seat 33 is provided between the valvecharnber and the reservoir, and an elongated valve stem 34 is -mountedin the body 10 for longitudinal reciprocal movement. A valve head 35 isconnected to the stern for movement between a position in contact withthe seat for closing the valve and preventing ow of air from thereservoir to the valve chamber, as Shown in Fig. l, and a position inspaced relation to the valve seat for opening the valve. The stem 34also mounts a slide valve 36 which opens upon closing of the head 35 toexhaust air from the rear end 14 of the cylinder.

An arcuate trigger guard 40 is extended from the housing 11 to thehandle 25, and a trigger 41-is pivotally connected to the body 10 andoperatively associated with the valve stern 34 for longitudinallyreciprocating the stem to open and to close the valve 28.

An elongated tubular piston 46 is mounted in the cylinder 12 forlongitudinal reciprocal movement between the forward and rearward ends13 and 14 thereof. A pair of longitudinally spaced front and rearO-rings 47 are mounted in circumscribing relation to the piston forslidyable sealing engagement with the housing 11 in its portions ofdifferent diameters. The piston has an open, internally threadedforwardly disposed female socket 48, and a plug 49 is screw-threadedinto the socket. A coupling pin 50 is journaled in the plug and isextended substantially diametrically of the cylinder 12. It is to benoted that the piston has a rear head 51 in opposed relation to the cap20 and that there is a fluid leakage path 52 in circumscribing relationto the head and the circumjacent housing.

The body 10 also includes an elongated generally rectangular nose orbarrel portion or channel member 55 having a circumscribing flange 56fitted against the open forward end 13 of the cylinder 12 and connectedto the housing 11 by means of a plurality of bolts 57 extended throughthe flange and into the housing. The nose portion provides an elongated,transversely generally rectangular passageway or channel 59 having alongitudinal center line extended substantially coaxially forwardly ofthe cylinder 12 and terminating in an open forward end 60. As best seenin Fig. 4, the nose portion also provides a pair of lower laterallyoutwardly extended flangeways 61, Van upper open notch 62 slightly widerthan the passageway and opening endwardly of the nose portion, and asubstantially rectangular window 64 downwardly opening from thepassageway on the opposite side of the nose portion from the notch. Anannular resiliently compressible shock absorbing bumper cushion 66 isconcentrically fitted in the cylinder 12 against the flange forengagement by the piston 46 during extension thereof. It is also to benoted that the nose portion has a central wall 68 and a pair of spacedside walls 69 laterally extended from the central wall on opposite sidesof the channel or passageway. i

An elongated driving blade 70 provides a rear coupling end 71 extendedthrough a diametrically extended slot in the plug 49 and connected tothe coupling pin 50. The blade has a forward driving end 72 fitted inthe passageway 59, and includes a pair of lower laterally outwardlyextended flanges 73 individually slidably fitted in the tlangeways 61for guided movement of the blade longitudinally in the passageway. Itwill be evident that upon reciprocal movement of the piston 46 in thecylinder 12, the blade is reciprocally moved in the passageway. With theexception of the notch 62 in the nose portion 55, the structuredescribed to this point is conventional and forms a suitable environmentfor the present invention. It will be evident that the blade 70 andpiston 46 constitute a driving assembly for workpieces engaged by theblade.

The subject invention provides an elongated pusher bar 75 including ashank 76 of substantially rectangular cross section preferablyintegrally connected to the driving blade 70 and having a pusher head 77larger than the shank and iitted in the passageway 59 for movementtherein with the blade. The head has a forward abutting surface 78 whichis spaced axially inwardly from the terminal end 72 of the drivingblade, as best seen in Figs. l and 3.

The present invention also provides a depth control head including asubstantially circular disk, plate, or simulated hammer head 86, havinga forwardly disposed convex workpiece engaging Surface 87 and adiametrically extended slot 88. The head includes a substantiallyrectangular tongue or mounting portion 89 perpendicularly extended fromthe disk and fitted in the notch 62 of the nose portion 55 for slidablemovement longitudinally of the nose portion. When mounted in thismanner, the disk is disposed transversely of the nose portion forwardlyof the open end 60 thereof with the slot in alignment with the drivingblade 70. The tongue has an upwardly disposed central recess 90 havingabutment shoulders 91 and 92 at the forward and rearward ends thereof,respectively. As will be apparent, the head can be employed to attain adimpling function and when so to be employed preferably has the convexsurface 87. When to be used for depth control purposes without dimpling,the surface 87 is preferably at.

A retainer block or male member is connected to the upper surface of thenose portion 55 in spanning relation to the notch 62 and in overlayingslidable engagement with the tongue 89. More specifically, the retainerblock is fitted in the recess 90 of the tongue and provides front andrear edges 101 and 102 adjacent to the shoulders 91 and 92,respectively. Shoulder 92 engages the rear edge 102 to limit forwardlongitudinal slidable movement of the tongue. The retainer block isconnected to the nose portion by means of bolts 104 extended through theblock.

Conventionally a staple magazine is fitted in the Iwindow 64 of the noseportion 55 and connected to the nose by the bolts 104 extended throughthe nose portion into the magazine. The magazine includes a mechanism,generally indicated by the numeral 111, for feeding staples 112successively into the passageway into alignment with the slot 88 in thedisk 86 and the driving blade 70. Each of the staples includes a pair ofspaced parallel penetrating legs 113 interconnected by a crown 114.Inasmuch as the details of the magazine and the feeding mechanismthereof are conventional and form no specific `part of the subjectinvention, further discussion thereof is believed unnecessary. It is tobe understood, however, that the feeding mechanism `delivers thestaples, one by one, into the passageway so that the legs of the staplesare received in the ange ways 61, and so that the crowns thereof extendtransversely of the passageway in the path of travel of the bladewhereby the staples are driven longitudinally forwardly in the noseportion by the blade.

. Operation `The operationof the described' embodimentiof the subjectinventionis believed to belrea'clil-y apparenta'nd is-briefly summarizedatithislpoint'. In connection with thetoperationof the subjectinvention, reference'. is conveniently made to a stud 120 of a building,and to a wallboard 121 adapted for `connection to thestudand-in'-cluding a relatively thickcore layer 122 of gypsum or theilike coveredonopposite sides by relatively thin tearablesheathing 123 "of paper.

With" the tool in the condition shown in Fig. l and 'withl the handle'25 grasped in the hand of the operator, tlesurface 87 of the disk86iis1placed against thefwall: board\121with the slot 88" overthedesired locationI of the staple 112. The surface 87 may be pressedagainst the board by pressing inwardly on the handle and/ or thebuttftoffthe housing. 11 to hold the board against the studt120. Since`thevalve head35 is lseated',;.the, mani fold 1T is vented.` toythefatrnosphere throughithelslide valvet36`.` Since the space betweenthe t O-ringsv47 is connectedtothe reservoir: 26 by means ofthe bore 31,line pressure exists in said space andv against the forwardandwintermediate enlargementsiof the piston` circumscribed by theO-rings.:l When'the trigger 41l is squeezed,`

thevalve head 35 is unseated to admit line'pressureto theimanifold 17.Air pressure is applied againstA thefrear facefof therearenlargement 51by way of the `leakage path 52. f Since the effective area of this rearface against which air pressure is exerted is greaterlthan the effectiveforwardly disposedfsurface ofthe intermediate enlargement-.of` the`piston, the piston is shoved forwardly in the cylinder `and moves thedrivingy blade 70 forwardly in the passageway 59. The driving end 72 ofthe blade engagesarstaple1112, in a position to be driven in thepassageway, and slides the staple forwardly through the slot 881 in thedisk 86. The force of the blade also drives they staple into thewallboard 121 and the stud `120 therebehindtl Immediately followingentryof the driving end 72 .ofv the blade 70 into `the slot 88,-` the pusherhead 77 engages thewdisk`86 and slides thetongue 89 forwardly-in thentch62.` This` forces the `surface 87 of the disk inwardly'against thesheathing `123 andthe backing por-- tion 122 for substantiallyconcentrically dimpling lor de pressingtthe area circumscribing thelocation of the staple 112:1. Driving movement of thedisk is limited byen.- gagementof the piston 46 with the cushion 66;

Furthermore, the location `of the pushing head 77 in. relation to thedriving end 72 of the blade 70 limits pene;e tration` of the staple1125into the wallboard 121. Thus, ittwvill'benoted thatwhen thepusherhead 77 engages thel disk, the` drivingend of the blade is `axiallyspaced inward'- ly of the outer surface 87 of the disk. Thus,'the`driving blade 70cannot force the crown114 of the staple throughthe-.sheathing 123 `regardless'of the air pressure or the extent ofcompressionfof the cushion `66. As long as the diskissnheld againstthewallboard during the complete driving rstroke, the staple penetrates thepredetermined amount` This prevents tearing or fracturing of thesheathing and limits `movement lof the staple relatively inwardly of thewallboard to a position which rmly holds `the `sheathingvagainst thebacking portion of the wallboard and fdependably draws the wallboardagainst theilstud 120. Still further, the parts are so related thatthe.. crown114 of the staple is disposed inwardly of the non-dimpledouter surface of the wallboard and in contactwith the sheathing, as bestillustrated in Fig. 3. AS discussed above, the dimpled area isApreferably lled withV GOJ aplaster type of material, not shown, toconceal the. y

i indentation made in the wallboard and to cover the crowrvV When thetrigger 41 is released, the air rearward of thel pistoniis exhausted tothe atmosphere through thev valve 36fand the piston is retracted by theair pressureI in the portion of `the `chamber between `the O-rings and.gagement with the cushion 66.

thus withdraws the blade70 rearwardly inthe passage.- way 59- so that itisready for alsubsequent driving opera tion.. 'Ihe dimpling disk 86 ismoved toY retracted positionfsimply by pressing the disk against anotherarea of the wallboard into whichit is desired to drive a staple 112.l

It will be recalled that when the trigger 41 is actuated, the tool tendsto` recoil incident to movement of the piston. 46,` even before thestaple is driven from the tool. However, it will be evidenttthat whenthe disk 86 is in engagement with a workpiece at the instant of` triggeractuation, it either continues in workpiece engagement in spite oftherecoil` or immediately returns to workpiece engagement as soon as itis struck by the head 77. Thus, the described attachment automaticallycompensates for such recoil and obviates the previous necessity ofutilizing a blade capable of excessive` extension from the tool tocompensate for recoil.

The preferredrelationship of the extended end 72'of the `bladey for themounting of dry wallboard is shown in Figs. l and 3. If no dimpling isdesired, a disk 86 is employed providing a flat face at 87, as shown ina second` form of the invention soon to be described.

Incertain instances, such as in finish work, it is desirable tocountersink the staple, nail or other fastener. ln such event, the bladeis employed of such length that the extended end 72 thereof protrudesfrom the face 87 upon completion of its driving stroke.. An extensiontofapproximately one-sixteenth of an inch is usually appropriate for suchcountersinking.

If the outer end of the fastener is intended to be flush with the outersurface of a workpiece, a blade 70 is employed of such a length that itsouter end 72 is ilush with the outer surface of the disk-86 at the endoli-the full driving stroke.

l Secondform The second form of the invention is` illustrated in Figs..5' through 8 in which the conventional portions of the Ldriving toolare designated by the same numerals as pre'- viously employed anddescribed.

A depth control head is indicated generally at 125 .having asubstantially circular disk, plate, or simulated hammer head 126providing a forwardly disposed substan- `tially flat workpiece engagingsurface 127. The' disk has' a diametrically extended slot 128therethrough. As before, a convex surface may be utilized at 127, ifdimplin'g .is desired. The flat face is employed for the describedMcountersinking, flush nailing, and protruded nailing or staplingpreviously described. The head includes a tongue or mounting member 129constituting an abutment, perpendicularly extended from the disk andtted in the notch 62 of the nose portion 55 for slidable movementlongitudinally of the nose portion. Such mount- :ing disposes the disktransversely of the nose portion lforwardly lof the open end 60 with theslot`128 in align- .ment'withthe driving blade 70.

As best shown in Figs. 7 and 8, the nose portion 55 is :formed with anenlarged channel 130 along the blade '70. A plunger or mounting portion131 is slidably fitted vto the channel 130 and extends through the noseportion for reciprocal movement therein. The plunger provides anenlarged abutment head 132 within the cylinder 12 of the tool andslidably fitted to said cylinder for driv- :ing engagement by the piston46 and motion arresting en- It will be evident that Athe head 132 andtongue 129 define a recess therebetween Yinto which the central wall 68extends. A

t The plunger 131, the tongue 129, and its disk 126 are :interconnectedfor unitary reciprocal movement by cap' :screws 134 extended through thetongue and screwthreadably engaged in the plunger.

As best shown in Fig. 8, the lower surface of the plung.-` 'er 131 ismilled or otherwise formed to provide an elongated cavity of generallyU-shaped transverse cross-seciment independently of the plunger. Thecavity has spaced sides interconnected by a central portion. As before,the blade has a thin extended end portion 72 of a thicknesssubstantially that of the staple but rearwardly thereof is thickened forpurposes of rigidity. As described, the relationship of the extended endof the blade at the end of its driving stroke to the workpiece engagingsurface 1'27 of the disk 126 determines whether the staple or otherfastening member driven thereby is coun tersunk, liush with the surfaceof a workpiece into which it is driven, or protrudes. In the form shownin Figs. 5 through 8, the blade is of sufficient length to extend beyondthe disk 127 so a's to countersink the fastener.

In the second form of the invention, actuation of the cylinder 46 forcesthe driving blade forwardly to pick up the uppermost staple 112. Whenthe piston strikes the enlarged head 132 it forces the plunger 131 andthe depth control head 125 forwardly with the blade. As before, thedepth control head compensates for recoil and engages against thesurface of a workpiece 137 into which it is desired to drive the stapleto secure the workpiece against the stud 120. As the blade 70 drives thestaple or other fastener into the workpiece and stud, the disk isvigorously thrust against the workpiece to insure its tight engagementagainst the stud, thus achieving a simulated final hammer blow ininsuring proper workpiece engagement with the stud and proper fastenersetting. The device not only has the advantages incident to poweredactuation and retains the described effect of the final hammer blow but,by the provision of a blade having a length in proper relation to theoverall length of the unitary assembly of the disk 126, tongue 129,plunger 131, and enlarged head 132, dependably drives the staple orother fastener to the desired predetermined depth with respect to theouter surface of the workpiece engaged by the surface 127 of the depthcontrol head.

Although the invention has been herein shown and described in what isconceived to be the most practical and preferred embodiments, it isrecognized that departures may be made therefrom within the scope of theinvention,v which is not to be limited tothe details disclosed hereinbut is to be accorded the full scope of the claims so as to embrace anyand all equivalent devices and apparatus.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. In an apparatus for driving a U-shaped staple havmg a pair ofpenetrating prongs interconnected by a crown into a penetrable workpieceincluding a core layer covered by a flexible tearable sheathing therebyto hold the sheathing tightly against the backing portion withouttearing the sheathing with the crown of the staple, a body including anelongated nose portion providing an elongated channel longitudinallythereof terminating in an open end, an elongated mounting notch extendedinwardly from said open end and communicating rwith the channel, and alateral staple feeding window opening into a channel and spaced inwardlyfrom said open end; a workpiece dimpler including a dimpling platedisposed transversely endwardly of the nose portion including a staplereceiving slot aligned with the channel and an elongated tongueconnected to the plate and longitudinally slidably tted in the notch formovement between a dimpling position with the plate endwardly spacedfrom the nose portion in compressible engagement with the workpieceagainst the sheathing and a retracted position with the plate engagingthe nose portion over said open end; a retainer connected to the noseportion in bridging relation to the notch and overlaying the tongue forengagement therewith in said dimpling position to limit movement of theplate outwardly of the nose portion; means connected to the nose portionfor feeding staples into the channel through the window and intoalignment with the slot in the plate; an elongated staple driving blade.having a staple engaging end and an opposite cow 8 pling end mounted inthe channel for longitudinal recipro'cal movement therein from aposition retracted inwardly past the window to a staple driving positionextended into the slot in the plate to bring the engaging end intocontact with the staple thereby to slide the staple through the channeland the slot and into the workpiece within the area thereof compressedby the plate; a pusher head secured to the blade in longitudinallyinwardly spaced relation to the staple engaging end and movabletherewith in the channel for engagement with the dimpling plate to movethe plate into said dimpling position subsequent to initial movement ofa staple through the slot by the blade; and powered means in the bodyconnected to the coupling end of the blade for reciprocating the bladein the channel. 1

2. In a tool for forcing a driven member into a workpiece; an elongatedbody having forward and` rearward end portions and including a housingproviding a cylinder, and a channel member connected to` the housing andforwardly exteded therefrom to an end edge in forwardly spaced relationto the housing, the channel member providing an elongated channelcommunicating with the cylinder and in longitudinal alignment therewith;a depth control head including an elongated mounting portion slidablyfitted in the channel and a workpiece engaging plate connected to themounting portion and extended transversely of the end edge of thechannel member, the plate having a slot aligned with the channel, themounting portion providing a longitudinally extended recess def fined bylongitudinally spaced forward and rearward `abutments rigidlyinterconnected in fixed spaced relation; a male member accessibleexteriorly of the body including means releasably screw-threadablyconnected in longitudinally fixed relation to the channel member andextended into said recess between the forward and rearward abutments;means connected to the channel member for feeding driven members intothe channel into alignment with the slot in the plate; and powered meansmounted in the cylinder and the channel for longitudinal reciprocalmovement therein having a driving stroke for pushing a driven member inthe channel longitudinally thereof through the slot into a workpieceengaged by said plate, and a retraction stroke movable rearwardly behinda successive driven member in the channel, said powered means beingengageable with the depth control head during said driving stroke tomove the depth control head unitarily forwardly with said powered meansthereby to limit forward movement of the powered means with respect tothe head `and the slot in the plate, the forward and rearward abutmentsbeing respectively engageable with said male member during said.retraction and driving strokes to limit movement of the head `relativeto the body.

3. In a tool for driving a U-shaped staple into a workpiece, anelongated body having a forward end edge and an elongated channel havinga transverse polygonal crosssection; a depth control head including anelongated mounting portion having a transverse polygonal crosssectioncorresponding to that of the channel and longitudinally slidably fittedin the channel, the mounting portion also providing a longitudinallyextended cavity substantially coextensive with the channel and ofgenerally U-shaped transverse cross-section having spaced sides and acentral portion connecting the sides, the head further having aworkpiece engaging plate connectedto the mounting portion and extendedtransversely of the end edge of the body and the cavity, the plateproviding a rectangular slot of generally the same shape as said cavityand in registration therewith, the polygonally yfitted relationship ofthe channel and mounting portion constraining the mounting portion tosaid movement iongitudinally of the channel; means connected to'the bodyfor feeding a staple into the cavity against the central portion thereofand in longitudinal alignment with and rearwardly V of the slot; and anelongated driving blade having Aa rectangular cross-section similar tobut smaller than the slot and being longitudinally slidably itted in thecavity for movement between a driving position extended into the slotand a retracted position spaced rearwardly from the slot, the bladehaving a driving stroke movable from retracted to extended position intoengagement with a staple in the cavity to push the same outwardlythrough the slot and into a workpiece engaged by the plate.

4. In a powered tool for controllably driving an elongated fastener intoa workpiece, a housing having a cylinder therein; powered means axiallyreciprocally movable in the cylinder; an elongated nose portionreleasably connected to the housing and including a substantiallyrectangular central wall endwardly outwardly extended from the housingand terminating in an edge, and spaced side walls transversely extendedfrom the central wall, said walls defining an elongated channeltherebetween in longitudinal alignment and communicating with thecylindex', the channel having an open end adjacent to said end edge,said central wall having a notch extended inwardly therein from said endedge and communicating with the channel; an elongated plunger fitted inthe channel for longitudinal reciprocal movement therein having an outerend portion adjacent to the notch and an inner end portion within thecylinder; a depth control head including a tongue slidably fitted in thenotch and connected to said outer end portion of the plunger formovement therewith, the head also including a workpiece engaging plateconnected to the tongue and extended therefrom transversely of the openend of the channel, the plate being movable yinto and out of engagementsaid end edge incident to reciprocation of the plunger and having a slotaligned with the channel; means connected to the nose portion forfeeding such fasteners into the channel rearwardly of the slot and inalignment therewith; and a driving blade slidably fitted in the channeland against the plunger, in alignment with the slot and forreciprocation in the channel and relative to the plunger between aretracted position rearwardly of a fastener in the channel and anextended position engageable with such fastener for forcing the samethrough said slot into a workpiece engaged by the plate, said poweredmeans engaging the blade for moving the same from retracted to extendedposition, said powered means also engaging the inner end portion of theplunger during movement of the blade toward extended position forunitarily moving the blade and plunger toward extended position andthereby to limit the extent of travel of the blade through said slot.

5. The tool of claim 4 wherein the powered means is a iluid operated ramhaving a piston providing a substantially flat abutment surface extendedtransversely of the cylinder in opposed relation to the: flange; whereinthe inner end portio-n of the plunger has a at abutment surface incpposed relation to said abutment surface of the piston and engageablethereby during extending movement of said plunger to enable said unitarymovement; and wherein the blade is connected to the piston.

References Cited in the file of this patent UNITED STATES PATENTS

